<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <title>Document</title>
</head>

<body>
  <div id="app">
    <span v-if="isUser">
      <label for="username">User</label>
      <input type="text" id="username" placeholder="Please Input User" key='username'>
    </span>
    <span v-else>
      <label for="email">Email</label>
      <input type="text" id="email" placeholder="Please input emial" key='email'>
    </span>
    <button @click="isUser = !isUser">change</button>
  </div>


  <script src="../js/vue.js"></script>
  <script>
    const app = new Vue({
      el: '#app',
      data: {
        isUser: true
      }
    })
  </script>
</body>

</html>